An isolated measurement system typically includes a measurement system to measure external signals and a control system to control the measurement system and receive measurement data therefrom. The two systems operate in two different voltage domains that are galvanically isolated from each other. The measurement system often includes multiple channels, each with its own measurement system and converter. Each channel transmits sampled data, in an asynchronous manner, to the control system through a respective data communication transformer.
A power generator provided in a voltage domain of the control system generates power for a voltage domain of the measurement system. The power generator includes a power transmitter in the control system's domain coupled to a rectifier in the measurement system's domain via a transformer that bridges an isolation barrier between the two domains. The power transmitter and rectifier are active continuously to ensure power supply to the measurement system is continuous. A power monitor may measure a voltage supply provided by the rectifier and may generate power feedback data therefrom, which is communicated to the control system's domain via a dedicated isolation transformer.
Modern applications of isolated measurement systems call for sampling and conversion operations to be performed with increasing precision. The inventors have determined that the operations of the power transmitter and/or rectifier can inject undesired electromagnetic interference into the operation of such systems. Accordingly, the inventors have identified a need for an isolated measurement system in which a powered control system may deliver power to an otherwise unpowered measurement system and yet reduce electromagnetic interference that the power delivery might inject into operations of the measurement system. The inventors also have identified a need for such a system in which communication of power feedback data makes efficient use of isolators.